Hemangioblastomas can cause polycythemia due to ectopic production of erythropoietin as a paraneoplastic syndrome.

The outcome for hemangioblastoma is very good, if surgical extraction of the tumor can be achieved; excision is possible in most cases and permanent neurologic deficit is uncommon and can be avoided altogether if the tumor is diagnosed and treated early. Persons with VHL syndrome have a bleaker prognosis than those who have sporadic tumors since those with VHL syndrome usually have more than one lesion.

The majority of patients with neurocutaneous melanosis are asymptomatic and therefore have a good prognosis with few complications. Most are not diagnosed, so definitive data in not available. For symptomatic patients, the prognosis is far worse. In patients without the presence of melanoma, more than 50% die within 3 years of displaying symptoms. While those with malignancy have a mortality rate of 77% with most patients displaying symptoms before the age of 2.

The presence of a Dandy-Walker malformation along with neurocutaneous melanosis, as occurs in 10% of symptomatic patients, further deteriorates prognosis. The median survival time for these patients is 6.5 months after becoming symptomatic.

Hemangioendothelioma is used to describe a group of vascular neoplasms that may be considered benign as well as malignant, depending on the specific group member's activity.

A neuroectodermal tumor is a tumor of the central or peripheral nervous system.

Treatment is varied and depends on the site and extent of tumor involvement, site(s) of metastasis, and specific individual factors. Surgical resection, radiotherapy, and chemotherapy have all been used to treat these masses, although studies on survival have yet to be conducted to delineate various treatment regimens.

In order to remove it completely, surgery may be an option.It relieves the hydrocephalus (excess water in the brain) about half of the time.

Another treatment is chemotherapy, recommended for patients with severe problem.

It was previously a relatively common complication of the massive lymphedema of the arm which followed removal of axillary (arm pit) lymph nodes and lymphatic channels as part of the classical Halstedian radical mastectomy, as a treatment for breast cancer. The classical radical mastectomy was abandoned in most areas of the world in the late 1960s to early 1970s, being replaced by the much more conservative modified radical mastectomy and, more recently, by segmental breast tissue excision and radiation therapy. Because of this change in clinical practice lymphedema is now a rarity following breast cancer treatment—and post-mastectomy lymphangiosarcoma is now vanishingly rare. When it occurs following mastectomy it is known as Stewart-Treves syndrome (which can be both lymphangiosarcoma and hemangiosarcoma following mastectomy). The pathogenesis of lymphangiosarcoma has not been resolved, however several vague mechanisms have been proposed. Stewart and Treves, proposed that a cancer causing agent is present in lymphedematous limbs. Schreiber "et al." proposed that local immunodeficiency as a result of lymphedema results in a "immunologically privileged site" in which the sarcoma is able to develop.

Choroid plexus tumors are a rare type of cancer that occur from the brain tissue called choroid plexus of the brain. These tumors usually occur in children younger than 2 years and are classified according to the WHO classification of the tumors of the central nervous system:

- Choroid plexus carcinoma (WHO grade III)

- Choroid atypical plexus papilloma (WHO grade II)

- Choroid plexus papilloma (WHO grade I)

Symptoms vary depending on the size and location of the tumor and typically include headaches, nausea and vomiting, irritability, and decreased energy.

Ependymomas make up about 5% of adult intracranial gliomas and up to 10% of childhood tumors of the central nervous system (CNS). Their occurrence seems to peak at age 5 years and then again at age 35. They develop from cells that line both the hollow cavities of the brain and the canal containing the spinal cord, but they usually arise from the floor of the fourth ventricle, situated in the lower back portion of the brain, where they may produce headache, nausea and vomiting by obstructing the flow of cerebrospinal fluid. This obstruction may also cause hydrocephalus. They may also arise in the spinal cord, conus medullaris and supratentorial locations. Other symptoms can include (but are not limited to): loss of appetite, difficulty sleeping, temporary inability to distinguish colors, uncontrollable twitching, seeing vertical or horizontal lines when in bright light, and temporary memory loss. It should be remembered that these symptoms also are prevalent in many other illnesses not associated with ependymoma.

About 10% of ependymomas are benign myxopapillary ependymoma (MPE). MPE is a localized and slow-growing low-grade tumor, which originates almost exclusively from the lumbosacral nervous tissue of young patients. On the other hand, it is the most common tumor of the lumbosacral canal comprising about 90% of all tumoral lesions in this region.

Although some ependymomas are of a more anaplastic and malignant type, most of them are not anaplastic. Well-differentiated ependymomas are usually treated with surgery. For other ependymomas, total surgical removal is the preferred treatment in addition to radiation therapy. The malignant (anaplastic) varieties of this tumor, malignant ependymoma and the ependymoblastoma, are treated similarly to medulloblastoma but the prognosis is much less favorable. Malignant ependymomas may be treated with a combination of radiation therapy and chemotherapy. Ependymoblastomas, which occur in infants and children younger than 5 years of age, may spread through the cerebrospinal fluid and usually require radiation therapy. The subependymoma, a variant of the ependymoma, is apt to arise in the fourth ventricle but may occur in the septum pellucidum and the cervical spinal cord. It usually affects people over 40 years of age and more often affects men than women.

Extraspinal ependymoma (EEP), also known as extradural ependymoma, may be an unusual form of teratoma or may be confused with a sacrococcygeal teratoma.

Lymphangiosarcoma is a rare malignant tumor which occurs in long-standing cases of primary or secondary lymphedema. It involves either the upper or lower lymphedematous extremities but is most common in upper extremities. Although its name implies lymphatic origin, it is believed to arise from endothelial cells and may be more accurately referred to as angiosarcoma.

Most heart tumors begin with myxomas, fibromas, rhabdomyomas, and hamartomas, although malignant sarcomas (such as angiosarcoma or cardiac sarcoma) have been known to occur. In a study of 12,487 autopsies performed in Hong Kong seven cardiac tumors were found, most of which were benign. According to Mayo Clinic: "At Mayo Clinic, on average only one case of heart cancer is seen each year." In a study conducted in the Hospital of the Medical University of Vienna 113 primary cardiac tumour cases were identified in a time period of 15 years with 11 being malignant. The mean survival in the latter group of patients was found to be .

Primary malignant cardiac tumors (PMCTs) are even more rare. A study using the Surveillance, Epidemiology and End-Results (SEER) Cancer Registry from 1973–2011 found 551 cases of PMCTs, with an incidence of 34 cases per million persons. The study also found that the incidence has doubled over the past four decades. The associated mortality was very high, with only 46% of patients alive after one year. Sarcomas and mesotheliomas had the worst survival, while lymphomas had better survival. When compared with extracardiac tumors, PMCTs had worse survival.

In breast pathology, pseudoangiomatous stromal hyperplasia, commonly abbreviated PASH, is an overgrowth of myofibroblastic cells and has an appearance similar to fibroadenomatoid changes.

The diagnostic significance is currently uncertain, but it appears to be benign. There have been cases of PASH diagnosed where the tumors co-exist with breast cancer. Other cases have made screening for breast cancer difficult and in some cases impossible due to the number and density of the existing PASH tumors. These cases have resulted in the necessity of a mastectomy and double mastectomy.

Hemangiosarcoma is a rapidly growing, highly invasive variety of cancer that occurs almost exclusively in dogs, and only rarely in cats, horses, mice, or humans. It is a sarcoma arising from the lining of blood vessels; that is, blood-filled channels and spaces are commonly observed microscopically. A frequent cause of death is the rupturing of this tumor, causing the patient to rapidly bleed to death.

The term "angiosarcoma", when used without a modifier, usually refers to hemangiosarcoma. However, glomangiosarcoma (8710/3) and lymphangiosarcoma (9170/3) are distinct conditions [in humans]. Hemangiosarcomas are commonly associated with toxic exposure to thorium dioxide (Thorotrast), vinyl chloride, and arsenic.

Once a patient with neurocutaneous melanosis becomes symptomatic, little can be done to improve prognosis as there is no effective treatment for the disorder. Most therapies are designed to treat the symptoms associated with the disorder, mainly those related to hydrocephalus. A ventriculoperitoneal shunt to relieve intracranial pressure is the preferred method.

Chemotherapy and radiotherapy have been shown to be ineffective in cases of neurocutaneous melanosis where malignancy is present. Additionally, due to the total infiltration of the central nervous system by these lesions, surgical resection is not a viable treatment option.

It has been demonstrated that early embryonic, post-zygotic somatic mutations in the NRAS gene are implicated in the pathogenesis of NCM. Recently, experimental treatment with MEK162, a MEK inhibitor, has been tried in a patient with NCM and progressive symptomatic leptomeningeal melanocytosis. Pathological studies with immunohistochemical and Western Blot analyses using Ki67 and pERK antibodies showed a potential effect of MEK inhibiting therapy. Further studies are needed to determine whether MEK inhibitors can effectively target NRAS-mutated symptomatic NCM.

Ependymoma is a tumor that arises from the ependyma, a tissue of the central nervous system. Usually, in pediatric cases the location is intracranial, while in adults it is spinal. The common location of intracranial ependymoma is the fourth ventricle. Rarely, ependymoma can occur in the pelvic cavity.

Syringomyelia can be caused by an ependymoma.

Ependymomas are also seen with neurofibromatosis type II.

Adult survivors of childhood cancer have some physical, psychological, and social difficulties.

Premature heart disease is a major long-term complication in adult survivors of childhood cancer. Adult survivors are eight times more likely to die of heart disease than other people, and more than half of children treated for cancer develop some type of cardiac abnormality, although this may be asymptomatic or too mild to qualify for a clinical diagnosis of heart disease.

Hemangiosarcoma is quite common in dogs, and more so in certain breeds including German Shepherd Dogs and Golden Retrievers. It also occurs in cats, but much more rarely. Dogs with hemangiosarcoma rarely show clinical signs until the tumor has become very large and has metastasized. Typically, clinical signs are due to hypovolemia after the tumor ruptures, causing extensive bleeding. Owners of the affected dogs often discover that the dog has hemangiosarcoma only after the dog collapses.

The tumor most often appears on the spleen, right heart base, or liver, although varieties also appear on or under the skin or in other locations. It is the most common tumor of the heart, and occurs in the right atrium or right auricular appendage. Here it can cause right-sided heart failure, arrhythmias, pericardial effusion, and cardiac tamponade. Hemangiosarcoma of the spleen or liver is the most common tumor to cause hemorrhage in the abdomen. Hemorrhage secondary to splenic and hepatic tumors can also cause ventricular arrythmias. Hemangiosarcoma of the skin usually appears as a small red or bluish-black lump. It can also occur under the skin. It is suspected that in the skin, hemangiosarcoma is caused by sun exposure. Occasionally, hemangiosarcoma of the skin can be a metastasis from visceral hemangiosarcoma. Other sites the tumor may occur include bone, kidneys, the bladder, muscle, the mouth, and the central nervous system.

Intravascular papillary endothelial hyperplasia (also known as "Masson's hemangio-endotheliome vegetant intravasculaire," "Masson's lesion," "Masson's pseudoangiosarcoma," "Masson's tumor," and "Papillary endothelial hyperplasia") is a rare, benign tumor. It may mimic an angiosarcoma, with lesions that are red or purplish 5-mm to 5-cm papules and deep nodules on the head, neck, or upper extremities.

In the 1960s, the incidence 5 years after a radical mastectomy varied from 0.07% to 0.45%.

Today, it occurs in 0.03% of patients surviving 10 or more years after radical mastectomy.

Angiosarcoma is a cancer of the cells that line the walls of blood vessels or lymphatic vessels. The lining of the vessel walls is called the endothelium. Cancers from the walls of blood vessels are called hemangiosarcomas, and cancers from the walls of lymphatic vessels are called lymphangiosarcomas. However, they should not be confused with cherry hemangiomas.

Most tumors of visceral blood and lymphatic vessel walls are cancerous (malignant). Because these cancers are carried by the blood flow or lymphatic flow, they can more easily metastasize to distant sites, particularly the liver and lungs.

Angiosarcomas will show signs of hemorrhage and necrosis. Pathologically, tumor cells will show increased nuclear to cytoplasm ratio, nuclear hyperchromasia, nuclear pleomorphism and high mitotic activity.

In dogs, hemangiosarcoma is relatively common, especially in larger breeds such as golden retrievers and Labrador retrievers. In humans, hemangiosarcomas and lymphangiosarcomas of the skin are uncommon. Angiosarcoma of the liver, a rare fatal tumor, has been seen in workers intensively exposed to the gas vinyl chloride monomer (VCM) for prolonged periods while working in polyvinyl chloride (PVC) polymerization plants. It has also been associated with individuals exposed to arsenic-containing insecticides and Thorotrast.

The management of PASH is controversial. Excision may be indicated in enlarging masses or lesions with atypical features.

Heart cancer is an extremely rare form of cancer that is divided into primary tumors of the heart and secondary tumors of the heart.

Familial and genetic factors are identified in 5-15% of childhood cancer cases. In <5-10% of cases, there are known environmental exposures and exogenous factors, such as prenatal exposure to tobacco, X-rays, or certain medications. For the remaining 75-90% of cases, however, the individual causes remain unknown. In most cases, as in carcinogenesis in general, the cancers are assumed to involve multiple risk factors and variables.

Aspects that make the risk factors of childhood cancer different from those seen in adult cancers include:

- Different, and sometimes unique, exposures to environmental hazards. Children must often rely on adults to protect them from toxic environmental agents.

- Immature physiological systems to clear or metabolize environmental substances

- The growth and development of children in phases known as "developmental windows" result in certain "critical windows of vulnerability".

Also, a longer life expectancy in children avails for a longer time to manifest cancer processes with long latency periods, increasing the risk of developing some cancer types later in life.

There are preventable causes of childhood malignancy, such as delivery overuse and misuse of ionizing radiation through computed tomography scans when the test is not indicated or when adult protocols are used.

Early detection is key. Untreated patients usually live 5 to 8 months after diagnosis.